An elastic liquid column, a fast-closing outlet valve, a pressure-wave probe, and a piston-type gas chamber are shown along a pipe. Set pipe length, initial velocity and closure time, choose whether the arrestor is connected and its gas volume, and compare the unprotected first peak with the simplified buffered estimate.
• A real-time 3D view with numbered, clickable parts: elastic liquid column; fast-closing outlet valve; pressure-wave probe; gas chamber and moving piston; transient pressure gauge. Scene tools include home view, focus-selected-part, auto-rotate, expand and show/hide labels, and drag-to-orbit with pinch-to-zoom. • Experiment controls: upstream pipe length (5–50 m); initial water velocity (0.2–2 m/s); valve closure duration (0.01–1 s); connect gas arrestor; initial gas volume at line pressure (0.05–1 L), plus a show flow/process markers toggle, pause/resume, single-step buttons (0.1 s and 1 s), a playback-speed selector and a restart experiment action. • Live readouts: linear pressure forecast; unprotected first peak; selected first peak; round-trip wave time; illustrative compressed gas volume; above vapor-pressure threshold. A model response curve is drawn beside the 3D view and updates as you change controls. • A Curves & measurements tab with two live charts, the model equations as written in the simulator and snapshot readouts; an Experiments tab with 3 guided presets (rapid closure without arrestor; add compliance; close slowly) plus a model-verification bench, timestamped event log and copyable trial report. • A Learn & assess tab with 3 lessons (follow the system; connect the measurements; interpret the model), a 2-question knowledge check with reset, and a written model-scope statement.
Stopping a moving column produces a pressure rise ΔP₀ = ρaΔv × min[1, 2L/(a tc)], where a is wave speed and tc is closure time. A closure shorter than the round-trip time 2L/a is effectively instantaneous, while a slow closure reduces the first rise, which the close-slowly experiment shows.
The model describes the gauge pressure afterward as a decaying cosine around the line pressure with a period set by the round-trip time 2L/a.
With the arrestor connected, the model adds gas compliance Cgas = Vgas/(κ Pabs) against pipe compliance and scales the peak by √[Cpipe/(Cpipe + Cgas)]. A larger gas volume gives a bigger reduction. The piston moves to show an illustrative compressed gas volume.
This is a post-closure linear elastic-wave teaching forecast, not a method-of-characteristics solver or product sizing model. Cavitation, air release and reflected-wave boundary details are not solved, and one animation second represents 0.05 physical seconds.
A sudden change in flow velocity, such as quick valve closure, converts kinetic energy of the moving column into a pressure wave.
Its gas chamber adds compliance: the piston compresses the gas and absorbs part of the surge volume, lowering the peak pressure.
If closure takes longer than the pipe round-trip time, reflected relief waves arrive before closure finishes, limiting the first pressure rise.
No. The buffer estimate is a simplified lumped-compliance teaching forecast and is not a transient solver or a sizing method.